Struct MaybeEngineCell 

pub struct MaybeEngineCell<T> { /* private fields */ }

A Sync wrapper that may or may not contain a value.

When to choose this vs EngineCell

Use this when the global state has a clear “not yet installed” or “already torn down” state. Access is gated on the inner Option being Some, so all the try_* accessors return Option<...>, matching core::reactive::hook::try_get_current’s wording.

Field access rule

Same as EngineCell: inner is reached only through the hand-written get_inner / set_inner accessors; the struct-literal escape hatch is reserved for the new / default constructors.

Implementations

impl<T> MaybeEngineCell<T>

Accessor implementations for MaybeEngineCell.

pub fn get_inner(&self) -> &UnsafeCell<Option<T>>

Returns a shared reference to the backing UnsafeCell<Option<T>>.

pub fn set_inner(&mut self, val: UnsafeCell<Option<T>>) -> UnsafeCell<Option<T>>

Replaces the backing storage with val, returning the previous UnsafeCell<Option<T>>.

Arguments

• val: UnsafeCell<Option<T>> - The new backing storage to install.

Returns

• UnsafeCell<Option<T>> - The previous backing storage.

Implemented via core::mem::replace. MaybeEngineCell<T> carries the implicit Sized bound (it is T: Sized here because Option<T> is Sized only when T is); mem::replace therefore applies. The returned previous backing storage is the caller’s responsibility to drop.

Note: set_inner is currently unused by the rest of the module (the try_* paths go straight through raw pointer reads/writes). It is kept here as the Lombok-shaped counterpart for parity with EngineCell::get_inner, in case future code wants to swap the whole backing storage.

impl<T> MaybeEngineCell<T>

Constructor + accessors for MaybeEngineCell.

pub const fn new() -> Self

Creates an empty cell.

Struct literal is permitted by the field-access rule for the constructor only.

pub fn try_get(&self) -> Option<&'static T>

If the cell contains a value, returns a shared reference to it.

pub fn try_get_mut(&self) -> Option<&'static mut T>

If the cell contains a value, returns a mutable reference to it.

Safety

Exclusivity rules from EngineCell::get_mut apply - no other borrow on the same cell may be alive.

pub fn try_set(&self, value: T) -> Result<(), T>

Installs value into the cell. Returns Err(value) if the cell is already populated; the caller may then retry or drop it.

Reads through get_inner to inspect the current state without aliasing, then writes through UnsafeCell::get raw pointer.

pub fn try_take(&self) -> Option<T>

Removes and returns the contained value, leaving the cell empty.

pub fn try_replace(&self, value: T) -> Option<T>

Replaces the contained value, returning the old one.

Trait Implementations

impl<T> Default for MaybeEngineCell<T>

Default impl for MaybeEngineCell.

fn default() -> Self

Returns the “default value” for a type.

impl<T> Sync for MaybeEngineCell<T>

Marker that MaybeEngineCell<T> is safe to share across the wasm main thread under single-threaded access.